Characterization of SiC crystals by using deep UV excitation Raman spectroscopy

Raman spectroscopy using deep UV (DUV) light excitation has been applied to characterizing process-induced defects in surface layers in SiC. Raman spectra of P+-ion implanted and post annealed SiC have been measured as a function of dose level and annealing temperature. The recovery of the crystallinity and electrical activity have been evaluated. Precipitation of excess phosphorus was found in heavily doped specimens. High dose implanted and post annealed samples show uneven distribution of residual defects, which is demonstrated by mapping of Raman bandwidth. Damage in 4H-SiC surfaces, which were mechanically polished with various sizes of abrasives, has been evaluated from DUV micro-Raman measurements. The Raman analysis demonstrates that bandwidth and peak frequency can be used as monitors of the polish-induced damage. It is found that localized defects reducing free carrier density remain even after polishing with small sized abrasives.